Gas purifiers for removing impurities from impure gas are well known. These known purifiers typically have a housing in fluid communication with an inlet and an outlet. As impurity-sorbing material is located within the housing.
Considerable difficulty has been encountered in attempting to determine when this impurity-sorbing material has come to the end of its life. In general the impurity-sorbing material has come to the end of its life when it no longer sorbs the impurities in the impure gas. However it is difficult and expensive to determine the end of life of the impurity sorbing material by measuring the impurities in the outlet gas. For this reason recent Attempts to determine the end of life of the impurity-sorbing material have been centered around the impurity-sorbing material itself. Some prior end of life sensors have been placed in the gas stream; but placing the sensor there can cause contamination of the gas. Other prior end of life sensors ave experienced a wide variety of other problems.